Backing pad for abrasive disks



Get. 8, 1946. w. STEVER BACKING PAD FOR ABRASIVE DISKS Filed Sept. 15, 1943 2 Sheets-Sheet 1 m H w T U M m m w m H m N t 7 T '1 n A 5 A .l a"! L 1.1!. W a Q a m m FlCri @ai. fi fio w. STEVER BACKING PAD FOR ABRASIVE DISKS Filed Sept. 15, 1943 2 Sheets-Sheet 2 44 INVENTOR William Siever A TTORNE Y Patented Oct. 8, 1946 BACKING PAD FOR ABRASIVE DISKS William Stever, Philadelphia, Pa., assignor to The Budd Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 15, 1943, Serial No. 502,423

6 Claims. (Cl. 51-197) The invention relates to a support for circular abrasive disks, and more particularly to a disk or supporting pad which is stiff yet flexible to a certain degree and which preferably consists of a material such as vulcanized fibre.

Among the objects of the invention is a disk or backing pad of the indicated type which has more desirable characteristics of flexibility and. a longer life than the known forms of such disks.

The aforesaid objects of the invention and other advantages are mainly achieved by a disk of fibre which is provided with a circular beading at some distance from its periphery.

Contributory to the desired result are also the support of said disk by the head for holding it at or near the location of said beading.

The aforesaid and further objects and features of the invention will become more clearly understood from the illustration of two embodiments in the attached drawings and the following description thereof.

In the drawings:

Fig. 1 is a fragmentary view of an abrasive disk, its backing pad and its supporting head, certain central portions being broken away so as to make the underlying construction visible;

Fig. 2 is a section along line 2-2 of Fig. 1;

Fig. 3 is a view of the supporting head looked at in the same direction as in Fig. 1;

Figs. 4, 5 and 6 are views corresponding to Figs. 1, 2 and 3 yet of a different embodiment; and

Fig. 7 is a fragmentary section similar to Fig. 2 yet of a third embodiment.

In Figs. 1 to 3, a driven shaft I is attached to a supporting head II which has its central portion recessed and provided with an annular undercut shoulder l2. An outer marginal portion l3 of the body II is likewise recessed and offers a plane surface.

A circular disk or pad It consists of resilient stifi material such as vulcanized fibre. The outer annular zone of the disk I4 is substantially flat. Inwardly of the zone l5, the disk I4 is provided with an annular beading l6 which rests against the marginal portion l3 of the head II. The innermost portion I! of the disk I4 is slightly conical and slotted at 18 at certain intervals around its central opening. The inner margin of the disk l4 extends under the undercut shoulder l2 and is held firmly in place by squeezing said shoulder against it. The part of the body I I carrying the shoulder I2 may be of comparatively soft material such as aluminum which allows the deformation of the shoulder I2 so as to hold said disk.

. disk 46.

Exchangeably attached to the head II is an abrasive disk l9 by means of a central nut 20 screwed on the central cylindrical portion 2| of the body H. The member 20 has an outwardly flaring portion 22 which presses the abrasive disk I9 and the disk l4 against the conical recessed surface of the body II and presses, furthermore, the abrasive disk I9 against the shoulder 12.

The provision of the beading 16 in the backing disk or pad prevents to a considerable degree the warping of the disk which is commonly experienced with fibre disks without such beading. Moreover, the bead prolongs the life of the backing disk.

The embodiment shown in Figs. 4, 5 and 6, has again a driven shaft 25 screwed into a member 26 forming part of the supporting head 21, and the backing disk 28 has the flat outer portion 29 and an annular beading 30. However, the disk 28 is not directly fastened to the head 21 but is attached to an annular metal disc 3| by rivets 32 arranged in the beading 30. The member 21 is provided near its outer circumference with an annular recess 33 having along its inner circumference undercut segment shaped shoulders 34. These shoulders are evenly distributed over the circumference leaving spaces between them. The disk 3| has along its inner circumference inwardly directed sector shaped extensions 35 adapted to engage the shoulder 34 by rotation of the member 21 relative to the disk 3|. The movement-between these two members is limited by pins or other stops 36.

The central portion of the member 21 is recessed similarly to the first embodiment and the central portion of the abrasive disk 31 is held by a nut 38 screwed on the member 26.

The embodiment shown in Fig. 7 differs from the embodiment shown in Figs. 4 to 6 in the attachment of the backing disk 40 to its support til at 42 inwardly of the beading 43, the adhesive attachment of a layer 44 of fabric, rubber or other sheet material to the disk 40, and in the provision of a-similar beading 45 in the abrasive The disks illustrated in Fig. '7 may be used with the head shown in Figs. 4 to 6.

The invention is not restricted to the illustrated embodiments, but it is intended to cover all such further modifications which fall within the spirit of the invention and will occur to those skilled in the art.

What is claimed is:

1. Flexible disk for supporting abrasive means, said disk consisting of sheet material and comprising a wide substantiallly fiat annular marginal portion, an intermediate narrow annular portion forming a beading on one side and an open groove on the other side of the plane of said disk as defined by its said marginal portion and a central portion adapted for attachment to a supporting head, said beading and groove imparting to the disk added flexibility and reducing warping and breakage.

2. In a grinding or polishing device, a head adapted for connection to a driven shaft and a disk in the form of a web of substantially constant thickness throughout supported by said head and adapted for supporting abrasive material, an annular beading formed in one side and a corresponding open groove in the other side of said disk between its inner and outer margins resting against said head near the outer circumference of the latter, said beading and groove serving to improve the flexibility and the resistance against Warping and breaking of the disk.

3. Disk according to claim 1 and a sheet metal supporting disk of smaller diameter, said two disks being connected to each other in the region near to and including said beading, said sheet metal disk serving for the attachment of the beaded disk to a supporting head.

4. Disk in sheet form covered with abrasive material having an annular narrow. Zone axially offset to form a projection on one side and a groove on the other side, said zone being arranged at some distance inwardly from the periphery of the disk, said, projection and groove improving the flexibility and the resistance against Warping and breakage of the disk.

5. Disk according to claim 1 and a sheet metal disk of smaller diameter, said metal disk being attached to the flexible disk near to the inner circumference of said beading.

6. Backing disk for a disk covered with abrasive material comprising a flexible sheet provided with an annular beading on one side and a corresponding open groove on the other side at a distance inwardly from its outer periphery, a thin layer of soft material adhesively attached to the flexible disk, said beading and groove and said layer of soft material improving the flexibility of the disk and increasing its resistance against Warping and breaking.

W'HiLIAM STEVER. 

